Augusto Gonzalvo

The learning curve of pedicle screw placement: how many screws are enough?

Study Design. A retrospective study. Objective. Assess the learning curve of pedicle screw (PS) placement of a Spinal Surgery Fellow (SSF) with no previous experience with the technique. Summary of Background Data. Recent studies have attempted to identify the learning curve for different surgical procedures to define training requirements. Several authors have described a learning curve for PS placement. However, no one has defined the number of PS necessary to be competent in this skill. Methods. All patients who had PS inserted by the SSF under the supervision of an Attending Spinal Consultant (ASC) and had adequate postoperative radiographs and computed tomography scans available, were included in this study. PS position was assessed by 2 blinded independent observers using a grading scale. PS placement by the SSF was evaluated by examining the assessed position in chronological groups of 40 screws. Results. Ninety-four patients underwent internal fixation of the spine with 582 PS. Eight cases (40 screws) were excluded because of lack of imaging studies. Of the 542 screws under evaluation, 320 (59%) were performed by the SSF, 187 (34.5%) by the ASC, and 35 (6.5%) by advanced orthopedic or neurosurgical trainees. The rate of misplaced PS performed by the SSF for the first 80 PS was 12.5% and dropped to 3.4% for the remaining 240 screws, which is a statistically significant difference (P < 0.01). Evaluation of computed tomography of vertebrae with PS placed by the SSF on one side and by the ASC on the other showed that the ASC achieved better placement during the first 80 PS (P < 0.01). However, this difference disappeared in the last 240 (P = 1.00). Conclusion. The findings demonstrate a learning curve for PS placement. In this series, the asymptote for this technique for an inexperienced SSF, started after about 80 screws (approximately 25 cases).

Single-level/single-stage Debridement and Posterior Instrumented Fusion in the Treatment of Spontaneous Pyogenic Osteomyelitis/discitis: Long-term Functional Outcome and Health-related Quality of Life

Study Design Retrospective study. Objective To support single-level posterior debridement and instrumented interbody fusion as a single-stage procedure for spontaneous pyogenic osteomyelitis/discitis. Summary of Background Data The best surgical technique for patients with bacterial spinal infections is still a matter of debate. Recent publications suggest that titanium implants can be used safely in the infectious sites in combination with debridement and antibiotic therapy. Methods We retrospectively review patients with spontaneous pyogenic osteomyelitis/discitis in whom medical therapy failed, and they consequently underwent posterior decompression and instrumented fusion. Data was collected regarding demographics, clinical presentation, images and laboratory studies, antibiotic treatment, duration of hospitalization, time to achieve radiologic evidence of fusion, postoperative complications, and neurologic function pre- and postoperatively. Quality of life was measured using the EQ5D questionnaire and level of disability with the Oswestry Disability Index. Results Nine patients, ranging in age from 41 to79 years, with a Frankel score of D in 7 cases and of E in 2 cases, underwent a single-level/single-stage debridement and posterior instrumented fusion with pedicle screws and an interbody and posterolateral autogenous bone graft. Preoperative neurologic deficits improved in all the cases and solid bone fusion was achieved in all 9 patients at 12 months. The mean follow-up period was 67 months. The infection healed after surgery in all the patients and they did not require a second operation to remove the metal implants. Quality of life assessed with the EQ5D questionnaire showed scores ranging between 0.70 and 1. The median Oswestry Disability Index was 15.5%. Conclusions These findings support that debridement and posterior instrumented fusion can be performed as a single-stage procedure with no increase in the recurrence rate or morbidity. The outcome has been satisfactory in our patients in terms of the rate of fusion and quality of life.

Symptomatic concurrent spinal epidural lipomatosis and spinal pathology.

Spinal epidural lipomatosis (SEL) is a rare condition defined by an excess deposition of extradural adipose tissue. SEL is often an incidental finding and the majority of patients remain asymptomatic. SEL is typically associated with excess steroid, either endogenous or exogenous, as well as a number of endocrinopathies. Few reports have described the disorder in conjunction with other spinal pathologies. A 47-year-old man presented to our hospital following a 14-day history of progressive paraparesis and gait disturbance. He had no significant past medical history and clinical examination demonstrated bilateral decreased power and pyramidal signs of his lower limbs. Magnetic resonance imaging (MRI) of his whole spine demonstrated dorsal thoracic epidural lipomatosis and a focal central disc extrusion at T6/7 with canal stenosis and increased cord signal (Fig. 1). Because of the ventral location of the disc and the presence of dual pathology (ventral compression by the disc and multilevel dorsal compression by the lipomatosis) he underwent a combined anterior and posterior approach, decompression and instrumented fusion (Fig. 3a). Histopathology of excised fat confirmed SEL. There were no perioperative complications, and at 4 weeks follow–up, there was near complete resolution of his lower limb weakness and gait disturbance. A 70-year-old man was referred with a 4-week history of midthoracic back pain and progressive lower limb numbness. Relevant past medical history included Wegener’s granulomatosis treated with 5–10 mg of prednisolone daily for 5 years and had no recent history of trauma. Clinical examination demonstrated reduced sensation with a sensory level of T6 and mild motor deficit in the lower limbs. Osteopenia and a T6 burst fracture with mild retropulsion was noted on his CT, while MRI suggested extensive SEL (T4 to L2) with spinal cord compression (Fig. 2). The patient developed worsening lower limb weakness and new urinary incontinence during a 5-day period of conservative management. Subsequently, he underwent an extensive T3–10 posterior decompressive laminectomy and instrumented fusion (Fig. 3b). Histopathology again confirmed SEL. At 12-month follow-up, the patient was continent and mobilizing independently with a frame. We present two novel cases of neurological deficit resulting from acute spinal pathology in pre-existing SEL. Symptomatic SEL in the Fig. 1. Case 1: (a) preoperative sagittal T1-weighted images and (b) preoperative sagittal T2-weighted images.

Lymphoma of the trigeminal nerve – the need for histological diagnosis

Abstract CNS lymphoma involving the trigeminal nerve is a rare condition which presents as a cavernous sinus lesion. It may mimic the radiological appearance of other lesions, and biopsy is essential before considering empirical radiotherapy for lesions in this region. We report the radiological, histopathological and operative findings of a primary non Hodgkin B cell lymphoma involving the trigeminal nerve.

Correlation between pedicle size and the rate of pedicle screw misplacement in the treatment of thoracic fractures: Can we predict how difficult the task will be?

Abstract Study Design. A retrospective study. Objective. To correlate the incidence of pedicle-screw (PS) misplacement with the dimensions of the pedicles in the treatment of thoracic spine fractures. Summary of background data. The technical challenge of internal fixation with PS in the thoracic spine has been well documented in the literature. However, there are no publications that document the correlation between the pedicle dimensions of the thoracic vertebrae in the preoperative computed tomography scans (CT) and the rate of PS misplacement. Methods. All patients who had PSs inserted between the T1 and T12 vertebrae during a 24-month period were included in this study. PS position was assessed on high quality CT scans by two independent observers and classified in 2 categories: correct or misplaced. The transverse diameter, craniocaudal diameter and cross-sectional area of the pedicles from T1 to T12 were measured in the pre-operative CT. Results. During the period of this study 36 patients underwent internal fixation with 218 PS. Of the 218 screws, 184 (84.5%) were correct and 34 (15.5%) were misplaced. Misplacement rate was 33% for pedicles with a transverse diameter less than 5 mm, 10.7% for those with a transverse diameter between 5 and 7 mm and 0% for those with a transverse diameter larger than 7 mm. There was a statistically significant difference in the rate of PS misplacement in pedicles with transverse diameter smaller than 5 mm compared with the others. Also, those with transverse diameter between 5.1 and 7 mm compared with those bigger than 7 mm in diameter. The rate of PS misplacement was higher between T3 and T9 (p < 0.05), which in turn correlated with pedicle transverse diameter. Conclusion. The rate of PS misplacement in the mid thoracic spine (T4–T9) is high and correlates with pedicle transverse diameter.

Intradural extramedullary colorectal adenocarcinoma metastasis to the cervical spine

Intradural metastases of non-neurogenic origin are rare, representing less than 4% of all spinal metastases, and only approximately 70 intradural extramedullary tumours have been reported in the literature to date. To our knowledge only three such lesions have metastasised from a colorectal primary. We report a case of an intradural extramedullary colorectal adenocarcinoma metastasis to the cervical spine causing spinal cord compression. A 60-year-old man presented with a 3-week history of intractable neck pain, bilateral upper limb pain and paraesthesia and left arm weakness. He had a history of locally advanced T4N2M0 rectal adenocarcinoma diagnosed 4 years prior, for which he had undergone pelvic exenteration with neoadjunctive chaemoradiotherapy. He subsequently developed metastatic disease and had sequentially undergone right upper lobectomy, left lower lobe wedge resection and right-sided adrenalectomy for metastases. In 2011 he underwent left stereotactic suboccipital craniotomy and excision of a cerebellar metastasis followed by whole brain radiotherapy. His MRI cervical spine (Figs 1,2) revealed an intradural extramedullary mass, measuring 8 × 17 mm, with compression of the spinal cord at the C3 level and compression of the exiting left C3 nerve root. The patient underwent excision of the lesion. C2 to C4 laminectomy and excision of the left C3/4 facet joint was performed to widely expose an intact dura with no evidence of an extradural lesion. Longitudinal durotomy revealed a tan-coloured extramedullary mass adherent to the undersurface of the dura. (Fig. 3) This was carefully reflected from the dura and arachnoid layer of the spinal cord and excised en bloc with the assistance of an operating microscope. The dura was repaired with a running 6.0 Nylon suture and reinforced with a collagen matrix patch (DuraGen; Integra, Plainsboro, NJ, USA) and fibrin sealant (TISSEEL; Baxter, Deerfield, IL, USA). The cervical spine was stabilised with lateral mass screws and connecting rods (Vertex; Medtronic, Minneapolis, MN, USA) from C2 to C5. A lumbar drain was inserted, and the patient was placed in a soft cervical collar. The post-operative course was uncomplicated, with no new or worsened neurological deficit. Histological analysis confirmed the lesion to be adenocarcinoma of colorectal origin. At the 6-week post-operative review the patient’s wound was well healed, and he was able to mobilize independently. While intradural extramedullary metastases can occur at any level the majority appear to occur in the lumbar spine. Lower cerebrospinal fluid (CSF) flow velocities in the lumbar spine may predispose this region to a higher probability of tumour cell settling. This is an important distinction between intradural extramedullary and epidural metastases, which are more commonly present in the cervical spine and the conus. All carcinoma types are able to metastasise to the leptomeninges with the vast majority of breast or lung origin. Adenocarcinoma is the predominant histological diagnosis. A number of routes of spread have been postulated. These include (i) haematogenous spread via the arterial pathway or retrograde via the venous plexus; (ii) extension along perineural lymphatics; (iii) direct transdural invasion; and (iv) tumour cell dissemination via the CSF. Intracranial metastatic tumours have been detected in 90% of patients with intradural metastases suggesting that tumour dissemination as ‘drop metastases’ via the CSF may be the predominant route of spread for these lesions. Furthermore patients with a posterior fossa tumour are more likely to develop a leptomeningeal lesion than those with a supratentorial metastasis. Suki investigated the relative risk of leptomeningeal disease in patients with a metastatic posterior fossa lesion treated with surgical resection or stereotactic radiosurgery and found that piecemeal resection of a posterior

Radiation induced malignant peripheral nerve sheath tumour of the second cervical nerve

We report a 44-year-old with progressive quadriparesis due to a dumbbell malignant peripheral nerve sheath tumour (MPNST) of the second cervical nerve, 17 years after whole brain radiotherapy for a pineal germinoma. To our knowledge this is the first case of radiation induced high cervical MPNST arising from a benign neurofibroma.

Radiological evaluation of C1 pedicle screw anatomic feasibility.

C1 pedicle screw instrumentation is a recently documented technique, which may have benefits over other more popularised procedures, however it may not be possible in all patients. This study aims to investigate the applicability of the C1 pedicle screw technique to a cohort of patients through assessment of radiological parameters. A retrospective review of 150 consecutive patients undergoing computer tomography (CT) of the cervical spine was performed. Based on defined parameters images were assessed for feasibility of placement of pedicle screws. C1 pedicle height (PH), pedicle width (PW), screw trajectory length (LML) and width (LMW) were recorded with PH  ≥ 4 mm defined as the primary outcome measure. A total of 115 patients and 230 C1 pedicles were examined. The mean PH was found to be 5.1 mm. 207 pedicles were deemed suitable for placement of pedicle screw instrumentation. Overall C1 pedicle screw instrumentation was deemed possible in 94.6% of male pedicles and 84% of female pedicles. C1 pedicle screw instrumentation is feasible to be performed in more than 90% of the patients.

Case report: Angiosarcoma of the cervical spine

Angiosarcomas (ASs) are rare malignant vascular tumours, which only occasionally occur in the spine. The prognosis is generally poor due to rarity of the condition as well as lack of data of treatment options. We present the case of a 75-year old man with a primary angiosarcoma of C2 and C3 who underwent occipito-cervical (to C6) fixation. A first biopsy did not result in a diagnosis and a further anterior approach with repeat biopsy had to be undertaken. The patient received adjuvant radiotherapy and at 6-month follow-up there was no radiological progression of the angiosarcoma. ASs are a rare condition and due to paucity of data relating to management cases should be reported to aid understanding and development of guidelines for diagnosis and treatment.